android pdf viewer with vertical paging

Question

I am developing app for android which has pdf to view. The PDF are in build into the app, so I have to just load pdf to view correctly.

There should be no option to share and all other stuff, but the user should be able to zoom the pdf.

I have used mupdf but the pdf scrolls horizontally (ie. the pages are side-by-side), I want the pdf to scroll vertically. I have tried everything but I am not getting result.

Answer 1

Thx for answer posted by @Arunjyothis but i have provided below class where variable reference are present :

ReaderView.java

      public class ReaderView  extends AdapterView<Adapter>
        implements GestureDetector.OnGestureListener, ScaleGestureDetector.OnScaleGestureListener, Runnable {
...
 private Stepper mStepper;

    public ReaderView(Context context) {
        super(context);
        mGestureDetector = new GestureDetector(this);
        mScaleGestureDetector = new ScaleGestureDetector(context, this);
        mScroller = new Scroller(context);
        mStepper = new Stepper(this, this);
    }


    boolean mReflowChanged;

    @Override
    protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
        super.onLayout(changed, left, top, right, bottom);

        // "Edit mode" means when the View is being displayed in the Android GUI editor. (this class
        // is instantiated in the IDE, so we need to be a bit careful what we do).
        if (isInEditMode())
            return;

        View cv = mChildViews.get(mCurrent);
        Point cvOffset;

        if (!mResetLayout) {
            // Move to next or previous if current is sufficiently off center
            if (cv != null) {
                cvOffset = subScreenSizeOffset(cv);
                // cv.getRight() may be out of date with the current scale
                // so add left to the measured width for the correct position
                //if (cv.getLeft() + cv.getMeasuredWidth() + cvOffset.x + GAP/2 + mXScroll < getWidth()/2 && mCurrent + 1 < mAdapter.getCount()) {
                if (cv.getTop() + cv.getMeasuredHeight() + cvOffset.y + GAP / 2 + mYScroll < getHeight() / 2 && mCurrent + 1 < mAdapter.getCount()) {
                    postUnsettle(cv);
                    // post to invoke test for end of animation
                    // where we must set hq area for the new current view
                    mStepper.prod();

                    onMoveOffChild(mCurrent);
                    mCurrent++;
                    onMoveToChild(mCurrent);
                }

                //if (cv.getLeft() - cvOffset.x - GAP/2 + mXScroll >= getWidth()/2 && mCurrent > 0) {
                if (cv.getTop() - cvOffset.y - GAP / 2 + mYScroll >= getHeight() / 2 && mCurrent > 0) {
                    postUnsettle(cv);
                    // post to invoke test for end of animation
                    // where we must set hq area for the new current view
                    mStepper.prod();

                    onMoveOffChild(mCurrent);
                    mCurrent--;
                    onMoveToChild(mCurrent);
                }
            }

            // Remove not needed children and hold them for reuse
            int numChildren = mChildViews.size();
            int childIndices[] = new int[numChildren];
            for (int i = 0; i < numChildren; i++)
                childIndices[i] = mChildViews.keyAt(i);

            for (int i = 0; i < numChildren; i++) {
                int ai = childIndices[i];
                if (ai < mCurrent - 1 || ai > mCurrent + 1) {
                    View v = mChildViews.get(ai);
                    onNotInUse(v);
                    mViewCache.add(v);
                    removeViewInLayout(v);
                    mChildViews.remove(ai);
                }
            }
        } else {
            mResetLayout = false;
            mXScroll = mYScroll = 0;

            // Remove all children and hold them for reuse
            int numChildren = mChildViews.size();
            for (int i = 0; i < numChildren; i++) {
                View v = mChildViews.valueAt(i);
                onNotInUse(v);
                mViewCache.add(v);
                removeViewInLayout(v);
            }
            mChildViews.clear();

            // Don't reuse cached views if the adapter has changed
            if (mReflowChanged) {
                mReflowChanged = false;
                mViewCache.clear();
            }

            // post to ensure generation of hq area
            mStepper.prod();
        }

        // Ensure current view is present
        int cvLeft, cvRight, cvTop, cvBottom;
        boolean notPresent = (mChildViews.get(mCurrent) == null);
        cv = getOrCreateChild(mCurrent);
        // When the view is sub-screen-size in either dimension we
        // offset it to center within the screen area, and to keep
        // the views spaced out
        cvOffset = subScreenSizeOffset(cv);
        if (notPresent) {
            //Main item not already present. Just place it top left
            cvLeft = cvOffset.x;
            cvTop = cvOffset.y;
        } else {
            // Main item already present. Adjust by scroll offsets
            cvLeft = cv.getLeft() + mXScroll;
            cvTop = cv.getTop() + mYScroll;
        }
        // Scroll values have been accounted for
        mXScroll = mYScroll = 0;
        cvRight = cvLeft + cv.getMeasuredWidth();
        cvBottom = cvTop + cv.getMeasuredHeight();

        if (!mUserInteracting && mScroller.isFinished()) {
            Point corr = getCorrection(getScrollBounds(cvLeft, cvTop, cvRight, cvBottom));
            cvRight += corr.x;
            cvLeft += corr.x;
            cvTop += corr.y;
            cvBottom += corr.y;
        } else if (cv.getMeasuredWidth() <= getWidth()) {
//            // When the current view is as small as the screen in height, clamp
//            // it vertically
//            Point corr = getCorrection(getScrollBounds(cvLeft, cvTop, cvRight, cvBottom));
//            cvTop += corr.y;
//            cvBottom += corr.y;

            // When the current view is as small as the screen in width, clamp
            // it horizontally
            Point corr = getCorrection(getScrollBounds(cvLeft, cvTop, cvRight, cvBottom));
            cvRight += corr.x;
            cvLeft += corr.x;
        }


        cv.layout(cvLeft, cvTop, cvRight, cvBottom);

        if (mCurrent > 0) {
            View lv = getOrCreateChild(mCurrent - 1);
            Point leftOffset = subScreenSizeOffset(lv);
            /*int gap = leftOffset.x + GAP + cvOffset.x;
            lv.layout(cvLeft - lv.getMeasuredWidth() - gap,
                    (cvBottom + cvTop - lv.getMeasuredHeight())/2,
                    cvLeft - gap,
                    (cvBottom + cvTop + lv.getMeasuredHeight())/2);*/

            int gap = leftOffset.y + GAP + cvOffset.y;
            lv.layout((cvRight + cvLeft - lv.getMeasuredWidth()) / 2,
                    cvTop - lv.getMeasuredHeight() - gap,
                    (cvRight + cvLeft + lv.getMeasuredWidth()) / 2,
                    cvTop - gap);

        }

        if (mCurrent + 1 < mAdapter.getCount()) {
            View rv = getOrCreateChild(mCurrent + 1);
            Point rightOffset = subScreenSizeOffset(rv);
            /*int gap = cvOffset.x + GAP + rightOffset.x;
            rv.layout(cvRight + gap,
                    (cvBottom + cvTop - rv.getMeasuredHeight())/2,
                    cvRight + rv.getMeasuredWidth() + gap,
                    (cvBottom + cvTop + rv.getMeasuredHeight())/2);*/

            int gap = cvOffset.y + GAP + rightOffset.y;
            rv.layout((cvRight + cvLeft - rv.getMeasuredWidth()) / 2,
                    cvBottom + gap,
                    (cvRight + cvLeft + rv.getMeasuredWidth()) / 2,
                    cvBottom + rv.getMeasuredHeight() + gap);


        }

        invalidate();
    }

 public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
                           float velocityY) {
        if (mScaling)
            return true;

        View v = mChildViews.get(mCurrent);
        if (v != null) {
            Rect bounds = getScrollBounds(v);
            switch (directionOfTravel(velocityX, velocityY)) {

                case MOVING_UP:
                    if (bounds.top >= 0) {
                        // Fling off to the left bring next view onto screen
                        View vl = mChildViews.get(mCurrent + 1);

                        if (vl != null) {
                            slideViewOntoScreen(vl);
                            return true;
                        }
                    }
                    break;

                case MOVING_DOWN:
                    if (bounds.bottom <= 0) {
                        // Fling off to the right bring previous view onto screen
                        View vr = mChildViews.get(mCurrent - 1);

                        if (vr != null) {
                            slideViewOntoScreen(vr);
                            return true;
                        }
                    }
                    break;
            }
            mScrollerLastX = mScrollerLastY = 0;
            // If the page has been dragged out of bounds then we want to spring back
            // nicely. fling jumps back into bounds instantly, so we don't want to use
            // fling in that case. On the other hand, we don't want to forgo a fling
            // just because of a slightly off-angle drag taking us out of bounds other
            // than in the direction of the drag, so we test for out of bounds only
            // in the direction of travel.
            //
            // Also don't fling if out of bounds in any direction by more than fling
            // margin
            Rect expandedBounds = new Rect(bounds);
            expandedBounds.inset(-FLING_MARGIN, -FLING_MARGIN);

            if (withinBoundsInDirectionOfTravel(bounds, velocityX, velocityY)
                    && expandedBounds.contains(0, 0)) {
                mScroller.fling(0, 0, (int) velocityX, (int) velocityY, bounds.left, bounds.right, bounds.top, bounds.bottom);
                mStepper.prod();
            }
        }

        return true;
    }

...
}

Stepper.java

public class Stepper {
    protected final View mPoster;
    protected final Runnable mTask;
    protected boolean mPending;

    public Stepper(View v, Runnable r) {
        mPoster = v;
        mTask = r;
        mPending = false;
    }

    @SuppressLint("NewApi")
    public void prod() {
        if (!mPending) {
            mPending = true;
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
                mPoster.postOnAnimation(new Runnable() {
                    @Override
                    public void run() {
                        mPending = false;
                        mTask.run();
                    }
                });
            } else {
                mPoster.post(new Runnable() {
                    @Override
                    public void run() {
                        mPending = false;
                        mTask.run();
                    }
                });

            }
        }
    }
}

Answer 2

The solution to this for MuPDF 1.9a is simply changing the following variable in the file ReaderView.java;

private static final boolean HORIZONTAL_SCROLLING = true;

to

 private static final boolean HORIZONTAL_SCROLLING = false;

Answer 3

You can do by changing the horizontal values to vertical ( change all width related calculations to height ). Change onLayout() & onFling() as below:

    @Override
    protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
        super.onLayout(changed, left, top, right, bottom);

        // "Edit mode" means when the View is being displayed in the Android GUI editor. (this class
        // is instantiated in the IDE, so we need to be a bit careful what we do).
        if (isInEditMode())
            return;

        View cv = mChildViews.get(mCurrent);
        Point cvOffset;

        if (!mResetLayout) {
            // Move to next or previous if current is sufficiently off center
            if (cv != null) {
                cvOffset = subScreenSizeOffset(cv);
                // cv.getRight() may be out of date with the current scale
                // so add left to the measured width for the correct position
                //if (cv.getLeft() + cv.getMeasuredWidth() + cvOffset.x + GAP/2 + mXScroll < getWidth()/2 && mCurrent + 1 < mAdapter.getCount()) {
                if (cv.getTop() + cv.getMeasuredHeight() + cvOffset.y + GAP / 2 + mYScroll < getHeight() / 2 && mCurrent + 1 < mAdapter.getCount()) {
                    postUnsettle(cv);
                    // post to invoke test for end of animation
                    // where we must set hq area for the new current view
                    mStepper.prod();

                    onMoveOffChild(mCurrent);
                    mCurrent++;
                    onMoveToChild(mCurrent);
                }

                //if (cv.getLeft() - cvOffset.x - GAP/2 + mXScroll >= getWidth()/2 && mCurrent > 0) {
                if (cv.getTop() - cvOffset.y - GAP / 2 + mYScroll >= getHeight() / 2 && mCurrent > 0) {
                    postUnsettle(cv);
                    // post to invoke test for end of animation
                    // where we must set hq area for the new current view
                    mStepper.prod();

                    onMoveOffChild(mCurrent);
                    mCurrent--;
                    onMoveToChild(mCurrent);
                }
            }

            // Remove not needed children and hold them for reuse
            int numChildren = mChildViews.size();
            int childIndices[] = new int[numChildren];
            for (int i = 0; i < numChildren; i++)
                childIndices[i] = mChildViews.keyAt(i);

            for (int i = 0; i < numChildren; i++) {
                int ai = childIndices[i];
                if (ai < mCurrent - 1 || ai > mCurrent + 1) {
                    View v = mChildViews.get(ai);
                    onNotInUse(v);
                    mViewCache.add(v);
                    removeViewInLayout(v);
                    mChildViews.remove(ai);
                }
            }
        } else {
            mResetLayout = false;
            mXScroll = mYScroll = 0;

            // Remove all children and hold them for reuse
            int numChildren = mChildViews.size();
            for (int i = 0; i < numChildren; i++) {
                View v = mChildViews.valueAt(i);
                onNotInUse(v);
                mViewCache.add(v);
                removeViewInLayout(v);
            }
            mChildViews.clear();

            // Don't reuse cached views if the adapter has changed
            if (mReflowChanged) {
                mReflowChanged = false;
                mViewCache.clear();
            }

            // post to ensure generation of hq area
            mStepper.prod();
        }

        // Ensure current view is present
        int cvLeft, cvRight, cvTop, cvBottom;
        boolean notPresent = (mChildViews.get(mCurrent) == null);
        cv = getOrCreateChild(mCurrent);
        // When the view is sub-screen-size in either dimension we
        // offset it to center within the screen area, and to keep
        // the views spaced out
        cvOffset = subScreenSizeOffset(cv);
        if (notPresent) {
            //Main item not already present. Just place it top left
            cvLeft = cvOffset.x;
            cvTop = cvOffset.y;
        } else {
            // Main item already present. Adjust by scroll offsets
            cvLeft = cv.getLeft() + mXScroll;
            cvTop = cv.getTop() + mYScroll;
        }
        // Scroll values have been accounted for
        mXScroll = mYScroll = 0;
        cvRight = cvLeft + cv.getMeasuredWidth();
        cvBottom = cvTop + cv.getMeasuredHeight();

        if (!mUserInteracting && mScroller.isFinished()) {
            Point corr = getCorrection(getScrollBounds(cvLeft, cvTop, cvRight, cvBottom));
            cvRight += corr.x;
            cvLeft += corr.x;
            cvTop += corr.y;
            cvBottom += corr.y;
        } else if (cv.getMeasuredWidth() <= getWidth()) {
//            // When the current view is as small as the screen in height, clamp
//            // it vertically
//            Point corr = getCorrection(getScrollBounds(cvLeft, cvTop, cvRight, cvBottom));
//            cvTop += corr.y;
//            cvBottom += corr.y;

            // When the current view is as small as the screen in width, clamp
            // it horizontally
            Point corr = getCorrection(getScrollBounds(cvLeft, cvTop, cvRight, cvBottom));
            cvRight += corr.x;
            cvLeft += corr.x;
        }



        cv.layout(cvLeft, cvTop, cvRight, cvBottom);

        if (mCurrent > 0) {
            View lv = getOrCreateChild(mCurrent - 1);
            Point leftOffset = subScreenSizeOffset(lv);
            /*int gap = leftOffset.x + GAP + cvOffset.x;
            lv.layout(cvLeft - lv.getMeasuredWidth() - gap,
                    (cvBottom + cvTop - lv.getMeasuredHeight())/2,
                    cvLeft - gap,
                    (cvBottom + cvTop + lv.getMeasuredHeight())/2);*/

                        int gap = leftOffset.y + GAP + cvOffset.y;
            lv.layout((cvRight + cvLeft - lv.getMeasuredWidth())/2,
                    cvTop - lv.getMeasuredHeight() - gap,
                    (cvRight + cvLeft + lv.getMeasuredWidth())/2,
                    cvTop - gap);

        }

        if (mCurrent + 1 < mAdapter.getCount()) {
            View rv = getOrCreateChild(mCurrent + 1);
            Point rightOffset = subScreenSizeOffset(rv);
            /*int gap = cvOffset.x + GAP + rightOffset.x;
            rv.layout(cvRight + gap,
                    (cvBottom + cvTop - rv.getMeasuredHeight())/2,
                    cvRight + rv.getMeasuredWidth() + gap,
                    (cvBottom + cvTop + rv.getMeasuredHeight())/2);*/

                        int gap = cvOffset.y + GAP + rightOffset.y;
            rv.layout((cvRight + cvLeft - rv.getMeasuredWidth())/2,
                    cvBottom + gap,
                    (cvRight + cvLeft + rv.getMeasuredWidth())/2,
                    cvBottom + rv.getMeasuredHeight() + gap);



        }

        invalidate();
    }

And,

 public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
                           float velocityY) {
        if (mScaling)
            return true;

        View v = mChildViews.get(mCurrent);
        if (v != null) {
            Rect bounds = getScrollBounds(v);
            switch (directionOfTravel(velocityX, velocityY)) {

                case MOVING_UP:
                    if (bounds.top >= 0) {
                        // Fling off to the left bring next view onto screen
                        View vl = mChildViews.get(mCurrent + 1);

                        if (vl != null) {
                            slideViewOntoScreen(vl);
                            return true;
                        }
                    }
                    break;

                case MOVING_DOWN:
                    if (bounds.bottom <= 0) {
                        // Fling off to the right bring previous view onto screen
                        View vr = mChildViews.get(mCurrent - 1);

                        if (vr != null) {
                            slideViewOntoScreen(vr);
                            return true;
                        }
                    }
                    break;
            }
            mScrollerLastX = mScrollerLastY = 0;
            // If the page has been dragged out of bounds then we want to spring back
            // nicely. fling jumps back into bounds instantly, so we don't want to use
            // fling in that case. On the other hand, we don't want to forgo a fling
            // just because of a slightly off-angle drag taking us out of bounds other
            // than in the direction of the drag, so we test for out of bounds only
            // in the direction of travel.
            //
            // Also don't fling if out of bounds in any direction by more than fling
            // margin
            Rect expandedBounds = new Rect(bounds);
            expandedBounds.inset(-FLING_MARGIN, -FLING_MARGIN);

            if (withinBoundsInDirectionOfTravel(bounds, velocityX, velocityY)
                    && expandedBounds.contains(0, 0)) {
                mScroller.fling(0, 0, (int) velocityX, (int) velocityY, bounds.left, bounds.right, bounds.top, bounds.bottom);
                mStepper.prod();
            }
        }

        return true;
    }